In the 1970s, at the height of the Cold War, American military planners began to worry about the threat to US warplanes posed by new, radar-guided missile defenses in the USSR and other nations. In response, engineers at places like US defense giant Lockheed Martin’s famous “Skunk Works” stepped up work on stealth technology that could shield aircraft from the prying eyes of enemy radar.

The innovations that resulted include unusual shapes that deflect radar waves—like the US B-2 bomber’s “flying wing” design (above)—as well as carbon-based materials and novel paints. Stealth technology isn’t yet a Harry Potter–like invisibility cloak: even today’s most advanced warplanes still reflect some radar waves. But these signals are so small and faint they get lost in background noise, allowing the aircraft to pass unnoticed.

China and Russia have since gotten stealth aircraft of their own, but America’s are still better. They have given the US the advantage in launching surprise attacks in campaigns like the war in Iraq that began in 2003.

This advantage is now under threat. In November 2018, China Electronics Technology Group Corporation (CETC), China’s biggest defense electronics company, unveiled a prototype radar that it claims can detect stealth aircraft in flight. The radar uses some of the exotic phenomena of quantum physics to help reveal planes’ locations.

It’s just one of several quantum-inspired technologies that could change the face of warfare. As well as unstealthing aircraft, they could bolster the security of battlefield communications and affect the ability of submarines to navigate the oceans undetected. The pursuit of these technologies is triggering a new arms race between the US and China, which sees the emerging quantum era as a once-in-a-lifetime opportunity to gain the edge over its rival in military tech.